To reduce printhead carriage mass so as to obtain high carriage accelerations and velocities, ink jet printers are provided with ink reservoirs located off-board the carriages, ink in these reservoirs being used to replenish ink drawn from the printhead cartridge reservoirs during printing. The refill may take place continuously or intermittently. For continuous refilling, the off-board reservoirs may be connected via hoses to the printhead cartridges as shown for example in U.S. Pat. No. 5,369,429. For intermittent refilling as shown in U.S. Pat. Nos. 5,136,305, 4,967,207 and 4,968,998, the printheads are moved to a refill station where the printhead cartridges are refilled with ink from the off-board reservoirs.
Ink leakage is a particular concern in network printers using the intermittent type refill system. Such printers are frequently left running unattended for extended periods of time and, generally speaking, have larger off-board ink reservoirs. Therefore, the potential for catastrophic ink spillage exists if a leak should occur during a period when the printer is running unattended.